Integrated circuits find application in many of today's consumer electronics, such as cell phones, video cameras, portable music players, computers, etc. Integrated circuits may include a combination of active devices, passive devices and their interconnections.
A common active device within an integrated circuit is the metal-oxide-semiconductor field-effect transistor (MOSFET). A MOSFET generally includes a semiconductor substrate, having a source, a drain, and a channel located between the source and drain. A gate stack composed of a conductive material (i.e.—a gate) and an oxide layer (i.e.—a gate oxide) is typically located above the channel. During operation, an inversion layer forms a conducting bridge or “channel” between the source and drain when a voltage is applied to the gate. Both p-channel and n-channel MOSFET technologies are available and can be combined on a single substrate in one technology, called complementary-metal-oxide-semiconductor or CMOS.
Generally, the amount of current that flows through the channel of a transistor is directly proportional to the mobility of carriers within the channel region. Thus, the higher the mobility of the carriers in the transistor channel, the more current that can flow through the device and the faster it can operate. One way to increase the mobility of carriers in the channel of a transistor is to manufacture the transistor with a stressed channel. Depending upon the type of stressed channel (e.g.—tensile or compressive), significant carrier mobility enhancement has been reported for both electrons and holes.
A conventional technique employed to affect stress within the channel region of a MOSFET includes depositing a stress-inducing layer. Unfortunately, conventional stress-inducing layer deposition processes employ techniques that displace the stress-inducing layer too far from the channel region, thereby reducing its efficacy for promoting carrier mobility.
Thus, a need still remains for a reliable integrated circuit system and method of fabrication, wherein the channel of the integrated circuit system exhibits improved carrier mobility due to the application of a close proximity stress memorization layer. In view of the ever-increasing commercial competitive pressures, increasing consumer expectations, and diminishing opportunities for meaningful product differentiation in the marketplace, it is increasingly critical that answers be found to these problems. Moreover, the ever-increasing need to save costs, improve efficiencies, and meet such competitive pressures adds even greater urgency to the critical necessity that answers be found to these problems.
Solutions to these problems have been long sought but prior developments have not taught or suggested any solutions and, thus, solutions to these problems have long eluded those skilled in the art.